Embryogenesis and cell movement: Amphibian gastrulation.

Abstract

Fibroblasts and other tissue cells in culture exhibit various social behaviours such as contact inhibition of movement and contact guidance. Fibrous network of the extracellular matrix containing collagen, fibronectin, laminin and proteoglycans is the substratum for cell migration in many occasions during embryogenesis, including neural crest cell migration, primordial germ cell migration, neurite extension and gastrulation in echinoderm, avian, mammalian and amphibian embryos. Studies on amphibian gastrulation revealed that each embryonic mesoderm cell moves by extending lamel-lipodia and filopodia which attach to the extracellular fibril network on the inner surface of the ectoderm layer. There have been accumulating pieces of evidence that the fibril network serves as an adequate substratum for the mesoderm cell migration, and provides guidance by the mechanism of contact guidance caused by the alignment of fibrils along the blastopore and animal pole axis. Contact inhibition of movement is another mechanism which causes cell movement away from the blastopore region. Immunostaining has shown that the extracellular fibrils contain fibronectin and laminin.